<?php
class FileType {

	private static $_TypeList = array();
	private static $CheckClass = null;
	
	private function __construct($filename) {
		self::$_TypeList = $this->getTypeList();
	}

	/**
	 *处理文件类型映射关系表*
	 *
	 * @param string $filename 文件类型
	 * @return string 文件类型，没有找到返回：other
	 */
	private function _getFileType($filename) {
		$filetype = "other";
		/*
		if (!file_exists($filename)) {
			throw new Exception("no found file!");
		}*/
		
		$file = @fopen($filename, "rb");
		if (!$file) {
			throw new Exception("file refuse!");
		}
		
		$bin = fread($file, 15); //只读15字节 各个不同文件类型，头信息不一样。
		fclose($file);
			
		$typelist = self::$_TypeList;
		foreach ($typelist as $v) {
			$blen = strlen(pack("H*", $v[0])); //得到文件头标记字节数
			$tbin = substr($bin, 0, intval($blen)); ///需要比较文件头长度

			if (strtolower($v[0]) == strtolower(array_shift(unpack("H*",$tbin)))) {
				return $v[1];
			}
		}
		
		return $filetype;
	}

	/**
	 *得到文件头与文件类型映射表*
	 *
	 * @return array array(array('key',value)...)
	 */
	public function getTypeList() {
		return array(array("FFD8FFE1","jpg"),
				array("89504E47","png"),
				array("47494638","gif"),
				array("49492A00","tif"),
				array("424D","bmp"),
				array("41433130","dwg"),
				array("38425053","psd"),
				array("7B5C727466","rtf"),
				array("3C3F786D6C","xml"),
				array("68746D6C3E","html"),
				array("44656C69766572792D646174","eml"),
				array("CFAD12FEC5FD746F","dbx"),
				array("2142444E","pst"),
				array("D0CF11E0","xls/doc"),
				array("5374616E64617264204A","mdb"),
				array("FF575043","wpd"),
				array("252150532D41646F6265","eps/ps"),
				array("255044462D312E","pdf"),
				array("E3828596","pwl"),
				array("504B0304","zip"),
				array("52617221","rar"),
				array("57415645","wav"),
				array("41564920","avi"),
				array("2E7261FD","ram"),
				array("2E524D46","rm"),
				array("000001BA","mpg"),
				array("000001B3","mpg"),
				array("6D6F6F76","mov"),
				array("3026B2758E66CF11","asf"),
				array("4D546864","mid"));
	}

	public static function getFileType($filename) {
		if(!self::$CheckClass) self::$CheckClass=new self($filename);
		$class=self::$CheckClass;
		
		return $class->_getFileType($filename);
	}
}

?>